Media sheets for use in an image forming device are initially stored in an input area. The input area is sized to hold a predetermined number of media sheets that are stacked together. A pick mechanism is positioned adjacent to the input tray to pick individual media sheets from the stack and deliver them into a media path. The pick mechanism should accurately deliver one sheet from the input area, and should deliver the sheet in a timely manner.
The pick mechanism includes a pivoting arm having a pick roller at the distal end. The pick roller rests on the stack and rotates to drive the top-most sheet from the stack into the media path. The arm applies a downward force onto the media stack. This force applied through the roller increases the friction between the roller and top-most sheet such that the sheet is delivered to the media path by rotation of the roller.
One prior art device limited the amount of force applied to the media stack. A drawback of applying a limited force is that the roller may slip during rotation. Roller slip causes a delay in picking the media sheet from the stack and introducing the sheet into the media path. This delay may cause print errors as the toner image is not accurately aligned with the top edge of the media sheet.
Another prior art device increased the amount of force applied to the media sheet to prevent roller slip. However, increased force caused the pick roller to move multiple sheets from the media stack into the media path. This double feed results in a media jam as the combined sheets cannot be moved as a unit through the device. The jam required the operator to locate the jam, remove the media sheets, reset the device, and then resume image formation.